Data from: Socially cued developmental plasticity in web-building spiders

Background: Socially cued anticipatory plasticity (SCAP) has been proposed as a widespread mechanism of adaptive life-history shifts in semelparous species with extreme male mating investment. Such mating systems evolved several times independently in spiders and male reproductive success should critically depend on timely maturation and rapid location of a receptive and, ideally, virgin female. We experimentally investigated socially cued anticipatory plasticity in two sympatric, closely related Nephila species that share many components of their mating systems, but differ in the degree to which male reproductive success depends on mating with virgin females. Juveniles of both species were reared either in the presence or absence of virgin female silk cues. We predicted strong selection on socially cued plasticity in N. fenestrata in which males follow a highly specialized terminal investment strategy, but expected a weaker plastic response in N. senegalensis in which males lost the ability to monopolize females. Results: Contrary to our predictions, N. fenestrata males presented with virgin female silk cues did not mature earlier than siblings reared isolated from such cues. Males in N. senegalensis, however, showed a significant response to female cues and matured several days earlier than control males. Plastic adjustment of maturation had no effect on male size. Conclusions: Our results indicate that a strong benefit of mating with virgins due to first male sperm priority does not necessarily promote socially cued anticipatory plasticity. We emphasize the bidirectional mode of developmental responses and suggest that this form of plasticity may not only yield benefits through accelerated maturation, but also by avoiding costs of precipitate maturation in the absence of female cues.背景：社会线索诱导的预期可塑性（socially cued anticipatory plasticity, SCAP）被提出是一类广泛存在的适应性生活史转变机制，适用于雄性交配投入极高的一次生殖物种。这类交配系统在蜘蛛中独立演化多次，雄性的繁殖成功关键依赖于适时成熟以及快速定位可交配且理想情况下为处女的雌蛛。本研究针对两种同域分布、近缘的络新妇属（Nephila）蜘蛛开展了社会线索诱导预期可塑性的实验探究，二者共享诸多交配系统特征，但雄性繁殖成功依赖处女雌蛛交配的程度存在差异。两种蜘蛛的幼蛛均在有或无处女雌蛛蛛丝线索的环境下饲养。我们预测，对于雄性采取高度特化终端投资策略的N. fenestrata，社会线索诱导的可塑性会受到强烈选择；而对于雄性丧失雌蛛独占能力的N. senegalensis，其可塑性响应则较弱。 结果：与我们的预测相反，接触处女雌蛛蛛丝线索的N. fenestrata雄蛛并未比隔离于此类线索的同胞个体更早成熟。然而，N. senegalensis的雄蛛对雌蛛线索呈现出显著响应，其成熟时间比对照组雄蛛提前数日。成熟时间的可塑性调整并未影响雄性体型。 结论：本研究结果表明，因第一雄虫精子优先权而获得处女雌蛛交配的强大收益，并不一定会促进社会线索诱导的预期可塑性。我们强调了发育响应的双向模式，并提出这类可塑性不仅可通过加速成熟带来收益，还能在缺乏雌蛛线索时规避仓促成熟的代价。